This invention relates to water swellable absorbent articles made from crosslinked polyelectrolytes, methods for their preparation, and to a composition containing polyelectrolytes and polyamido-polyamine/epichlorohydrin adducts which is useful to make absorbent articles.
It is known from U.S. Pat. Nos. 3,669,103 and 3,670,731 that cross-linked polymeric sorbents can be sandwiched between flexible supports to achieve disposable diapers or dressings.
It is further known from U.S. Pat. Nos. 2,988,539; 3,393,168; 3,514,419 and 3,357,067 that water swellable cross-linked carboxylic copolymers can be prepared. However, these prior art copolymers are all crosslinked during copolymerization or crosslinked after polymerization with subsequent neutralization of the carboxylic acid groups to form water swellable polyelectrolytes and hence these prior art polyelectrolytes cannot be crosslinked in situ as a coating on a substrate or as a flexible film thereof.
The polyamido-polyamine epichlorohydrin adducts used herein have been used to cure water soluble polymers to water insoluble films as is shown by U.S. Pat. No. 3,224,986 to Butler, et al. However, this patent does not indicate how to make water swellable products.
The foregoing adducts are believed to be water soluble resins having a plurality of 3-hydroxy azetidinium, epoxy propyl, and chlorohydrin groups as is shown by Carr et al., J. Applied Polymer Science 17:721-735 (1973).